Immunomodulatory properties of the probiotic Propionibacterium freudenreichii surface proteome
Résumé
Propionibacterium freudenreichii is consumed in elevated amounts both as a cheese starter (1010 CFU/D/person in France) and as a probiotic bacterium, while its effect on health is poorly understood. We investigate its immunomodulatory properties, in a context of growing occurrence of inflammatory bowel diseases. Twenty strains were compared in this regard in vitro using human PBMCs (Peripheral Blood Mononuclear cells), revealing strain dependent cytokine stimulatory properties. They also afforded strain-dependent protection in vivo towards colitis. A fermented milk, exclusively fermented by P. freudenreichii, was developed and tested in a healthy piglet model. It promoted growth health of the piglets and delivered live and metabolically active propionibacteria to the gut. Its consumption reduced gut mucosa production of pro-inflammatory IL-8 and TNF-α. Among strains, a genomic, transcriptomic and proteomic approach revealed contrasted effects of propionibacterial surface compounds such as exopolysaccharides and proteins. Specific proteins are involved in immunomodulation, while capsular exopolysaccharides abolish it. The role of each key compound is presently investigated in an ANR project (Sarter SURFace against INflammation of the Gut) in a multidisciplinary approach involving 7 partners. Elucidation of molecular and cellular mechanisms, together with in vivo anti-inflammatory effects, will open new perspectives for the use of fermented dairy products containing P. freudenreichii addressing the needs of specific populations.